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Two constructions of LDPC codes based on pseudo-symplectic geometry over finite fields

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The Journal of China Universities of Posts and Telecommunications 2018年第2期25卷 49-59页

作者： wang xiuli Hao Yakun College of Science Civil Aviation University of China

F（2v＋ 1） q Based on the pseudo-symplectic space over q of characteristics 2, combining the definition of low density parity check （LDPC） codes with the knowledge of graph theory, two kinds of LDPC codes with larger girth are constructed. By the knowledge of bipartite graph and the girth properties of LDPC codes, both the girth of the code C（m1 ,2v ＋ 1 ,q） and the code C（m2 ,2v ＋ 1 ,q） are computed are 8. The girth is larger, the performance of LDPC codes is better. Finally, according to the properties of the check matrix and the linear relation between the column vectors of the check matrix, both the minimum distances of the two codes are obtained are 2q ＋ 2.

关键词： LDPC codes pseudo-symplectic geometry minimum distance girth

Consensus-Based Approach to Day-Ahead Joint Local Energy-Reserve Market Design Considering Uncertainties of Renewable Energy

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CSEE Journal of Power and Energy Systems 2023年第6期9卷 2076-2089页

作者： Yang Chen Jianxue wang Yao Zhang xiuli wang School of Electrical Engineering Xi'an Jiaotong UniversityXi'an 710049China Shaanxi Key Laboratory of Smart Grid Xi'an Jiaotong UniversityXi'an 710049China

The penetration of distributed renewable generationprovides green energy to the local energy system. However, theuncertainties it brings to the system are becoming more andmore unacceptable, making it difficult to efficiently operate thelocal energy system. In a foreseeable future, there could bean increasing number of flexible resources, such as naturalgas power plants and interruptible demands, which providesolutions to these uncertainties. In this paper, a novel day-aheadenergy market design for the local energy system is *** market allows its participants to trade day-ahead energyin a peer-to-peer approach. In addition, flexible resources canprovide up/down-ward reserves to the system through reservetrading, where the local system operator (LSO) takes chargeof reserve procurement. Then, to operate the market, a marketclearing model is proposed incorporating operating costs of theday-ahead and real time stages. A consensus-based approach isapplied which enables the market to clear in a decentralizedmethod. Finally, since the LSO bears the reserve procurementcosts as well as the operating costs in the real time stage,we then propose a cost reallocation model to transfer theexpenses to the renewables. Case studies demonstrate the validityand efficiency of the proposed market design, including localenergy trading facilitation, high and stable revenue preservation,high computation efficiency and prevention of strategic biddingbehaviors.

关键词： Consensus-based approach distributed optimization joint energy-reserve trading peer to peer

Distributed generation planning for diversified participants in demand response to promote renewable energy integration

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Journal of Modern Power Systems and Clean Energy 2019年第6期7卷 1559-1572页

作者： Can DANG Xifan wang Chengcheng SHAO xiuli wang School of Electrical Engineering Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory on Electrical Insulation and Power Equipment Xi’an Jiaotong UniversityXi’an 710049China

In modern distribution system,the distribution system operator(DSO)acts as a market facilitator and data manager as well as an energy supplier and operation *** this circumstance,the DSO should comprehensively consider the diversified participants of the modern distribution system when making investment decisions of distributed generation(DG).This paper proposes a DG planning model considering the behavior of the diversified participants,which are motivated to cooperate with distributed renewable energy resources to promote their integration,and to achieve the optimal DG investment *** optimization model takes a centralized structure but fully considers the preferences,profits and comfort levels of the aggregators and *** model is linearized into a mixed-integer linear programming(MILP)problem and is solved by *** of the case study show that when the DSO spares subsidies to the aggregators and consumers to encourage their participation in demand response(DR)programs,it earns more compared with providing no subsidies for DR *** is also demonstrated that the overall profit increases as the subsidies increase within a certain range,but decreases when the subsidies exceed this ***,the DSO needs to carefully choose the subsidization level to achieve the optimal utilization of renewable energy and demand *** optimal subsidization level is derived from the model proposed in this ***,this paper puts forward a new pattern to utilize the distributed renewable energy sources,and provides guidance in policy making and DR program implementation.

关键词： Aggregator Consumer Demand response Distributed generation Planning Renewable energy

Hot deformation behavior of a near alpha titanium alloy with/without thermal hydrogen processing

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Acta Metallurgica Sinica(English Letters) 2010年第2期23卷 106-112页

作者： Qing wang Dongli SUN xiuli HAN Weigong wang School of Materials Science and Engineering Harbin Institute o) Technology Harbin 150001 China

The true stress-true strain curves of Ti-6Al-2Zr-IMO-IV alloy with hydrogen were obtained by hot compression test. The microstructures of the alloy before and after thermo-compression were observed. The apparent activation energies of deformation were calculated for the alloy with and without hydrogen. The behavior and mechanism of deformation for hydrogenated Ti-6A1-2Zr-IMO-IV alloy at high temperature were analyzed. The relationship between hydrogenation time and hydrogen content at 800 ℃ can be expressed as the equation： CH（t）=1.2-1.2exp（-t/120）. The true stress-true strain curves of hot compression for Ti-6Al-2Zr-IMO-IV alloy with hydrogen first move down and then move up as hydrogen content increases. Appropriate hydrogen content can reduce the peak of flow stress to minimal value. The apparent activation energies of deformation of the alloy with 0.47% hydrogen content and without hydrogen were calculated as 140 kJ·mol^-1 and 390 kJ-mol^-1, respectively, at 800 ℃ and at strain rate 8.3×10^4 s^-1. The apparent activation energy of deformation increases when the strain rate enhances from 8.3×10^-4 s^-1 to 8.3×10^-2 s^-1.

关键词： Titanium alloy Thermal hydrogen processing Compression at high temperature Hot deformation behavior Apparent activa- tion energy of deformation Microstructure

The Reliability and Operational Test System of a Power Grid with Large-scale Renewable Integration

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CSEE Journal of Power and Energy Systems 2020年第3期6卷 704-711页

作者： Jianxue wang Jingdong Wei Yuchao Zhu xiuli wang School of Electrical Engineering Xi’an Jiaotong UniversityXi’an 710049China

This paper proposes a reliability and operational test system named XJTU-ROTS2017,characterized by large-scale renewable power integration and long-distance *** test system has 38 nodes,63 lines,15 transformers and 20 generators in three areas,with peak load 10,421 MW and total installed capacity 16050 *** primarily transmits from a resource-rich area to a load area,carrying wind/solar power *** determination of component parameters and grid topology is based on design manuals and typical *** test system can be conveniently applied to reliability evaluation and operation optimization of composite power systems integrating coal/hydro/solar/wind ***,the extended applications to AC/DC hybrid power systems and interconnected power systems are discussed.

关键词： Test system large-scale renewable energy reliability operation XJTU-ROTS2017

Network-Constrained Energy Consumption Game for Dynamic Pricing Markets

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CSEE Journal of Power and Energy Systems 2022年第2期8卷 548-558页

作者： Yifei wang xiuli wang Yi Kuang Qiao Peng Hongyang Zhao Zhidong wang the Shannxi Key Laboratory of Smart Grid School of Electrical EngineeringXi’an Jiaotong UniversityXi’an 710049China the State Grid Economic and Technological Research Institute Co. Ltd.Beijing 102209China

The electricity distribution network is experiencing a profound transformation with the concept of the smart grid,providing possibilities for selfish consumers to interact with the distribution system operator(DSO)and to maximize their individual energy consumption ***,this profitseeking behavior among consumers may violate the network constraints,such as line flows,transformer capacity and bus voltage magnitude ***,a network-constrained energy consumption(NCEC)game among active load aggregators(ALAs)is proposed to guarantee the safety of the distribution *** temporal and spatial constraints of an ALA are both considered,which leads the formulated model to a generalized Nash equilibrium problem(GNEP).By resorting to a well-developed variational inequality(VI)theory,we study the existence of solutions to the NCEC game ***,a two-level distributed algorithm is proposed to find the variational equilibrium(VE),a fair and stable solution to the formulated game ***,the effectiveness of the proposed game model and the efficiency of the distributed algorithm are tested on an IEEE-33 bus system.

关键词： Electricity distribution network generalized Nash equilibrium problem network-constrained energy consumption game two-level distributed algorithm variational equilibrium

Network transition security for transmission switching

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Journal of Modern Power Systems and Clean Energy 2019年第5期7卷 1105-1114页

作者： Shijun TIAN Xifan wang xiuli wang Chengcheng SHAO Rong YE State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong UniversityXi’an 710049China State Grid Fujian Power Economic Research Institute Fuzhou 350012China

The smart grid with flexible topologies receives intensive attention *** switching(TS)alters the power system topology during operation,and has been demonstrated for the advantage of economic and secure operation of power *** includes a chain of sequential switching actions which bring disturbances to the system if the switching actions are not properly ***,it is not considered or well-studied in existing *** this paper,a new multi-period TS model that considers the transition security and a two-stage iterative method are *** the TS model,we take into account the fact that only one line is permitted to switch up or down at a time and the security of each switching action is *** proposed iterative solution makes the TS model more tractable in *** studies on a 6-bus system and the IEEE 57-bus test system have verified the effectiveness of theproposed *** results show that:àthe consideration of transition security of TS is essential;`the transition path is directly related to secure and fast the transmission switching;′the proposed model and solution method give an effective way to determine the switching sequence and switching timing under transition security criteria.

关键词： Optimization Security analysis Topology control Transmission switching

Small-signal Stability Analysis and Improvement with Phase-shift Phase-locked Loop Based on Back Electromotive Force Observer for VSC-HVDC in Weak Grids

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Journal of Modern Power Systems and Clean Energy 2023年第3期11卷 980-989页

作者： Yongqing Meng Haibo wang Ziyue Duan Feng Jia Zhengchun Du xiuli wang State Key Laboratory of Electrical Insulation and Power Equipment Shaanxi Province Key Laboratory of Smart GridXi’an Jiaotong UniversityXi’an 710049China State Grid Henan Electric Power Corporation Maintenance Company Zhengzhou 450000China IEEE

Voltage source converter based high-voltage direct current(VSC-HVDC)transmission technology has been extensively employed in power systems with a high penetration of renewable energy ***,connecting a voltage source converter(VSC)to an AC weak grid may cause the converter system to become *** this paper,a phase-shift phaselocked loop(PS-PLL)is proposed wherein a back electromotive force(BEMF)observer is added to the conventional phaselocked loop(PLL).The BEMF observer is used to observe the voltage of the infinite grid in the stationaryαβframe,which avoids the problem of inaccurate observations of the grid voltage in the dq frame that are caused by the output phase angle errors of the *** VSC using the PS-PLL can operate as if it is facing a strong grid,thus enhancing the stability of the VSC-HVDC *** proposed PS-PLL only needs to be properly modified on the basis of a traditional PLL,which makes it easy to *** addition,because it is difficult to obtain the exact impedance of the grid,the influence of shortcircuit ratio(SCR)estimation errors on the performance of the PS-PLL is also *** effectiveness of the proposed PSPLL is verified by the small-signal stability analysis and timedomain simulation.

关键词： Phase-locked loop(PLL) small-signal model stability improvement voltage source converter based high-voltage direct current(VSC-HVDC) weak grid

Model-free Demand Response Scheduling Strategy for Virtual Power Plants Considering Risk Attitude of Consumers

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CSEE Journal of Power and Energy Systems 2023年第2期9卷 516-528页

作者： Yi Kuang xiuli wang Hongyang Zhao Tao Qian Nailiang Li Jianxue wang Xifan wang School of Electrical Engineering Xi’an Jiaotong UniversityXi’an 710049China Shaanxi Key Laboratory of Smart Grid Xi’an Jiaotong UniversityXi’an 710049China

Driven by modern advanced information and communication technologies,distributed energy resources have great potential for energy supply within the framework of the virtual power plant(VPP).Meanwhile,demand response(DR)is becoming increasingly important for enhancing the VPP operation and mitigating the risks associated with the fluctuation of renewable energy resources(RESs).In this paper,we propose an incentivebased DR program for the VPP to minimize the deviation penalty from participating in the power *** Markov decision process(MDP)with unknown transition probability is constructed from the VPP’s prospective to formulate an incentivebased DR program,in which the randomness of consumer behavior and RES generation are taken into ***,a value function of prospect theory(PT)is developed to characterize consumer’s risk attitude and describe the psychological factors.A model-free deep reinforcement learning(DRL)-based approach is proposed to deal with the randomness existing in the model and adaptively determine the optimal DR pricing strategy for the VPP,without requiring any system model ***,the results of cases tested demonstrate the effectiveness of the proposed approach.

关键词： Incentive-based demand response Markov decision process virtual power plant